Unraveling the Capacitive Effect in the Vacancy-Heterostructure Wte2/Mote2 for Hydrogen Evolution Reaction by the Grand Canonical Potential Kinetics

Heterostructure shows superior catalytic performance since it inherits the catalytic properties of the components, and has the advantages of van der Waals force. Herein, we build a vacancy-van der Waals heterostructure with MoTe 2 and WTe 2 which forms a capacitor during the reaction, and we remove one Te atom from the MoTe 2 surface to form a Te vacancy. We found that during the catalytic reaction, the differential capacitance can change regularly, which plays an important role in the energy barrier balance of the catalytic reaction, so that the reaction can proceed smoothly, and the reaction rate can be achieved in a controllable scope. Based on this structure, we used the recently developed grand canonical reaction kinetics of quantum mechanics (GCP-K) to explore the electrocatalytic performance, and to predict the Tafel slope and onset potential of the HER reaction that is 81.31 mv/dec and -0.55 V respectively through changing applied potential